Erwin Chemerinsky, the UC Irvine law school dean who has argued cases before the high court, believes the justices will rely on their own views of the Constitution to decide whether to overturn California's Proposition 8.

A month before the U.S. Supreme Court hears arguments over California's ban on same-sex marriage, President Obama is due to render his own verdict with a decision to join the legal battle or stay out of it.

His decision will be closely scrutinized by both sides of the bitterly debated issue. It's far less clear how much - or even whether - it will matter to the court.

Thursday is the deadline for filing "friend-of-the-court" briefs by nonparties in support of gay and lesbian couples and the city of San Francisco in their challenge to Proposition 8, the 2008 initiative that limited marriage to the union of a man and a woman.

It's usually a routine stop on the way to the court's chambers, but this one is different because of the prospect of a filing from Obama'sJustice Department. Gay-rights advocates, who pleaded for Obama's support for three years while the case moved through lower courts, are looking for him to throw the weight of his administration behind their cause in its most momentous test.

The Prop. 8 case, to be heard March 26, and a case scheduled the next day on the 1996 law known as the Defense of Marriage Act, which denies federal benefits to married same-sex couples, are "the most important cases the court is going to have for a long time," Socarides said.

The Obama administration has weighed in on the second case, arguing that the federal law is unconstitutional and that all laws treating people differently based on their sexual orientation are constitutionally suspect.

States' authority

But the president has remained silent on the legal arguments over a state's authority to ban same-sex marriage, even after his declaration a year ago that - after years of "evolving" - he supports the rights of gays and lesbians to wed. In the same interview, he said the issue should be left up to the states, a position he has appeared to move away from in more recent comments.

Obama added to the anticipation in an interview last week with KGO-TV. After noting that Solicitor General Donald Verrilli, the Justice Department's top Supreme Court litigator, "is still looking into" a position on Prop. 8, he said that his personal view is that "same-sex couples should have the same rights and be treated like everybody else."

But according to several legal analysts, the anticipation is probably not shared by the nine decision-makers in robes.

"In a case like this, where politics have clearly overtaken legal analytics, I really don't think anything the solicitor general files at the direction of a recently re-elected president, who campaigned on the issue, would have any effect ... on any justice," said Vikram Amar, a UC Davis law professor and former Supreme Court clerk.

He said the court has historically respected the views of the solicitor general, who is expected to stay above the political fray and provide a clear-eyed view of the facts and legal issues. But in this case, Amar said, the administration has no special expertise or access to information, and the justices are likely to dismiss its arguments as ideologically driven.

Justices have own views

Erwin Chemerinsky, the UC Irvine law school dean who has argued cases before the high court, went a step further.

"I don't think this is a case where (any lawyer's) briefs and arguments are likely to make a difference" because the justices will rely on their own views of the Constitution, he said.

It might be different if the administration were discussing impacts on federal agencies or the armed forces, Chemerinsky said, but "saying it's in favor of marriage equality isn't going to determine the outcome of the case."

Socarides disagreed.

"If they decide to enter the case, their brief will probably be the most important before the court," he said. "The position of the government on how it thinks we should treat our citizens - what could be more important?"

And a decision to stay out of the case, he said, would send a signal that "it's not important to the White House for the court to rule broadly" and declare a constitutional right for gays and lesbians to marry.

Thomas Goldstein, a veteran Supreme Court litigator and legal commentator, agreed that the Obama administration's actions would send a signal, but said the court wouldn't be its main recipient.

If the Justice Department weighs in, he said, it would serve largely as "a message to the country about the wrongness of homophobia."